key: cord-0767110-k4yh3nip authors: Cioffi, Ettore; Dilenola, Davide; Iuliano, Luigi; Polidoro, Alessandro; Casali, Carlo; Serrao, Mariano title: Reversible conduction block of peroneal nerve associated with SARS-CoV-2 date: 2021-10-14 journal: Neurol Sci DOI: 10.1007/s10072-021-05655-8 sha: 34258226973b1fda4bd688111c6c81bb662cbf95 doc_id: 767110 cord_uid: k4yh3nip BACKGROUND: The ongoing SARS-CoV-2 pandemic, which is dramatically spreading worldwide, is well known for its respiratory sequelae. Besides cases of Guillain-Barré Syndrome, encephalitis, hyposmia, the whole range of neurological complications due to SARSCoV-2 is still not well known. METHODS AND FINDINGS: Herein, we report a new case of COVID-19, associated with mononeuropathy with reversible conduction block (CB). After SARS-CoV-2 infection, the patient developed acute weakness of left peroneal muscles. He underwent an endovenous immunoglobulin treatment, and symptoms improved. Two electroneurographic exam (before and after treatment), showed a reversible CB on left peroneal nerve. Dosage of serum antiganglioside antibodies showed anti-GM1 IgM positivity. CONCLUSIONS: The present case gives new informations about reversible CB neuropathy as an acute presentation of SARS-CoV-2. Besides, antiganglioside antibodies evaluation could be useful to understand etiology of the increasing number of neurological manifestations related to SARS-CoV-2. showed anti-GM1 IgM positivity (index 53.4; normal value 0-50). Clinical, laboratory, and neurophysiological findings were consistent with mononeuropathy with reversible CB associated with anti-GM1 antibodies. However, we had to exclude other pathologic situations such as compressive causes, or Slimmer's paralysis [4] . These etiologies were unlikely, since the patient did not assume prolonged positions which could cause compression of peroneal nerve [5] , nor had traumas, hematomas, or loss of weight (Slimmer's paralysis). Also, systemic causes of peroneal neuropathy were excluded since the normalcy of laboratory results. Thus, the patient was treated with a 5-day protocol of intravenous immunoglobulins (IVIg) at the dosage of 0.4 g/kg/ day, with subsequent improvement. On 03 February 2021, the patient underwent a follow-up neurophysiologic exam (T2), which was normal (Table 1 ; Fig. 1 ). To date, several cases of SARS-CoV-2-associated GBS have been reported [6] ; although, no other cases of SARS-CoV-2 infection associated with mononeuropathy with reversible CB have been described. It is possible that the aforedescribed event may remain isolated, and a relapse may not occur, but also it could represent the onset of a disease belonging to the symmetric or asymmetric CIDPs' spectrum (such as multifocal motor neuropathy, or Lewis-Sumner neuropathy, or "classical" CIDP) [7] , further considering the remarkable improvement with IVIg therapy. Although, we cannot totally exclude the possibility of spontaneous improvement. To be sure, regular clinical and neurophysiological follow-ups will need to be carried out, to define if the present case represents an isolated one, or any of the abovementioned relapsing-remitting dysimmune neuropathies. Seen the novelty of COVID-19 immunopathology, anti-GM1 antibodies may represent a new etiopathogenic mechanism underlining COVID19-related reversible CB neuropathy, although in our case we have mildly increased levels of antibodies, given their low level (i.e., 53.4; upper value 50). During SARS-CoV-2 disease, complexes of gangliosides are targeted by autoantibodies in GBS and its variants, being the GD1a/GD1b one of the most frequent [6] . Also, anosmia in COVID-19 could be explained by antiganglioside antibodies, seen the conspicuous expression of GD1a gangliosides in the olfactory bulb [8] . The present case gives a new information about reversible CB neuropathy as a possible acute presentation of SARS-CoV-2. Besides, antiganglioside antibody evaluation could be useful to understand etiology of the increasing number of neurological manifestations related to SARS-CoV-2. Author contribution Material preparation, data collection, and analysis were performed by Ettore Cioffi, Alessandro Polidoro, Luigi Iuliano, and Davide Dilenola. The first draft of the manuscript was written by Ettore Cioffi. All authors read and approved the final manuscript. Mariano Serrao and Carlo Casali supervised the final version of the manuscript. Ettore Cioffi and Davide Dilenola contributed equally to the paper. Data availability Raw data and materials are available upon request. Ethical approval This study has been approved by our appropriate ethics committee (Ethical Committee of Sapienza University-Comitato Etico Lazio 2) and has been performed in accordance with the ethical standards laid down in the Declaration of Helsinki of 1964 and its later amendments. Severe COVID-19 pneumonia: pathogenesis and clinical management Systemic manifestations of COVID-19 Neurological manifestations of COVID-19: a systematic review and current update Slimmer's paralysis-peroneal neuropathy during weight reduction COVID-19 proned ventilation and its possible association with foot drop: a case series Guillain-Barré syndrome spectrum associated with COVID-19: an up-to-date systematic review of 73 cases Chronic inflammatory demyelinating polyneuropathy: update on diagnosis, immunopathogenesis and treatment Physiology of gangliosides and the role of antiganglioside antibodies in human diseases Informed consent was obtained from the patient. Also, the patient signed informed consent regarding publishing its data.